Unsticking a stuck diesel - PeachParts Mercedes-Benz Forum

strelnik · #1 05-28-2009, 09:34 PM

I am buying a diesel (OM615) that has sat under cover for several years but ran well when it was in a car. It was removed because the body rotten tho' the drive train was good. It is now sticking.

I'd be interested in all the suggestions for what to do before attempting to unstick it.

The obvious things are:
1. Change all oil and oil filter
2. Change all fuel filters and reprime
3. Check and or change the glow plugs
4. Drain and refill the oil sump in the injection pump.

I have been advised that the only thing to do is use lot of WD40 in the cylinders after removing the injectors, and I have some doubts about that.

Others have said I MUST pull the head.

I favor adding a thin oil to every cylinder for about a week through the injector ports with a long injector-type oil can and slowly turning by hand.

Others have suggested using Rislone instead of oil, still others Ford ATF (Type F) because of its higher detergent content, compared to Dexron.

Whaddaya think?

I'm sure this thread will provide some good advice and some good discussion.

Thanks,
S (still looking for a running OM 636 for the 170DS to be)

leathermang · #2 05-28-2009, 10:15 PM

"I favor adding a thin oil to every cylinder for about a week through the injector ports with a long injector-type oil can and slowly turning by hand."

That is what I prefer also...
and it worked with a 1957 Mercury 312 I had which sat for more than 20 years... I am worried about you saying ' it is sticking'... which sounds like you have tried to move it without the procedure being followed first... which has the chance of breaking a ring...

strelnik · #3 05-28-2009, 11:05 PM

Quote:

Originally Posted by leathermang

"I favor adding a thin oil to every cylinder for about a week through the injector ports with a long injector-type oil can and slowly turning by hand."

That is what I prefer also...
and it worked with a 1957 Mercury 312 I had which sat for more than 20 years... I am worried about you saying ' it is sticking'... which sounds like you have tried to move it without the procedure being followed first... which has the chance of breaking a ring...

Nope, have never touched it. That's just a midwestern way of saying it's stuck.

Just like you guys say: All y'all

bigblockchev · #4 05-29-2009, 01:49 AM

I have found that hydraulic pressure through the injector or glowplug port will unstick any known engine. I use the same hydraulic pump that I use for my pop tester. Something like a Porta power pump with the appropriate fitting to connect to the injector or glowplug will work. It is a good idea to put some lube oil down every cylinder and let it sit for a few days to work it's way into the rings and such. You have to choose the cylinder which is on the compression stroke with both valves closed for this to work , or you can remove the cam which closes all the valves. Needless to say that the other injectors have to be out at the time. When the engine begins to budge try the starter motor to see if it will go, or you can use the big bolt on the front of the crankshaft but use care not to break it off with too much force. The hydraulic system applies pressure evenly and at the same time pushes lube oil where it is needed. If you can't get it loose with this it ain't never coming apart. Cheers Dan

t walgamuth · #5 05-29-2009, 05:54 AM

I would think with a hydraulic pump it would be possible to collapse a piston.

I have gotten more than one unstuck by soaking with tranny fluid and then bumping the starter repeatedly. Maybe bump it twenty times and try again the next day.

If this does not work after a week or two teardown is necessary.

On the hydraulic pump idea, since the alternative might be a teardown it might be argued that it woudn't be that much of a loss if you collapsed a piston, but the pistons do cost about 200 new and usually they can be reused on a rebuild.

Good luck!

leathermang · #6 05-29-2009, 11:06 AM

The main problem is not the force... but being sure a stuck ring does not break during the initial movement... so whatever you use later use plenty of patience in trying to get it into condition to make that first 1/4 inch movement....
The stuck ring could break a land on the piston too....

oldsinner111 · #7 05-29-2009, 11:10 AM

I would remove injectors,pour Marvel Mystery Oil in each hole.Let sit for 24 hours.Then gently try to free engine with injectors still out.

Diesel911 · #8 05-29-2009, 11:29 AM

I go with the Marvel Mystery Oil soal.
However, it negates the idea as to why the Engine won't rotate to begin with which is most likely Rust.
If you free the Engine up and run it like that it will be the Piston Rings scraping the rust off of the cylinder walls. This will not improve the life of the engine.
Pulling the Cylinder Head off allows you to view just how much of a problem you have and allows you to sand off the rust in the areas that you can reach.
Also, the last stuck Engine that I experienced had sat out side for several years in an area with extremem temp fluctuations and coolant had leaked into 3 of 6 cylinders. The result of this corroded the Aluminum of the pistons as well as rusted the Steel parts.

I took the Engine apart and even pulle out the Crank so I could get the Block mounted so that I could use a cutoff 3x3 inside of the Cylinders to hit on with a Sledge Hammer.
Never got any of the pistons to move and I sold all for scrap metal.

KCM · #9 05-29-2009, 01:05 PM

If it was running when parked, it likely is not stuck very hard. I agree with putting some oil or Marvel Mystery oil in the cylinders and letting it soak a few days. You could also simply add some diesel fuel to each of the cylinders as it is thinner.

I would use hydraulic pressure as a last resort as that can do major damage, and it should never be used on a piston that is a top dead center or at the bottom of the stroke (no leverage on the crankshaft and can bend the rod). Instead, remove the starter and use a pry bar on the the starter teeth. You can get a massive amout of leverage there. Don't worry about breaking a tooth, as they are a lot stronger than you would think. Just don't pry on only a corner, but get as much of the bar on the tooth as you can.

I would definitely try to get the unstuck and engine running before considering disassembly. Any damage will already be done once it is unstuck, then you can see if there really is any damage.

Gene Horr · #10 05-29-2009, 01:33 PM

I've never worked on a frozen engine and so am applying experience working on other old machinery which may not apply. This is just a wild idea but if the engine is on a mount that allows you to rotate the entire assembly what about rotating it once to get oil on the exposed bottom of the cylinder walls and hopefully on the bottom of the rings?

Also what about rotating it in both directions when working it loose to get the oil spread in both directions?

Diesel911 · #11 05-29-2009, 03:01 PM

[QUOTE=Gene Horr;2212192]I've never worked on a frozen engine and so am applying experience working on other old machinery which may not apply. This is just a wild idea but if the engine is on a mount that allows you to rotate the entire assembly what about rotating it once to get oil on the exposed bottom of the cylinder walls and hopefully on the bottom of the rings?

Also what about rotating it in both directions when working it loose to get the oil spread in both directions?[/QUOTE]

The Factory Service Manual claims rotating the Engine backwards can cause the timing chain to jump a tooth or teeth and if enough teeth are jumped cause damage to the Engine when it is run.
On other makes of Engines rotating backwards may not cause any problems

Diesel911 · #12 05-29-2009, 03:09 PM

Quote:

Originally Posted by t walgamuth

I would think with a hydraulic pump it would be possible to collapse a piston.

I have gotten more than one unstuck by soaking with tranny fluid and then bumping the starter repeatedly. Maybe bump it twenty times and try again the next day.

If this does not work after a week or two teardown is necessary.

On the hydraulic pump idea, since the alternative might be a teardown it might be argued that it woudn't be that much of a loss if you collapsed a piston, but the pistons do cost about 200 new and usually they can be reused on a rebuild.

Good luck!

I believe as long as the Hydraulic Pressure is kept at or below what the pressure of combustion inside of the cylinder would be I do not think it would be possible to collaspe a Piston.
May be one of the Engineers on the forum knows what the combustion pressure is and would tell us.

I think I would be more worried about deforming the Cylinders as the max combustion pressure takes place up near the top of the Cylinders. The pressure is less when the piston is at the bottom of the stroke.

Diesel911 · #13 05-29-2009, 03:18 PM

Another thought. What if one of the pistons is stuck at the bottom of its stroke.

When I was in Trade School the local Marine Salvage Surplus place would give us a bunch of Cummins Engines bought surplus that often had standing water in the Cylinders.
Were were tasked with taking all of them apart and trying to get enough good parts and assemble as many running Engines as we could piece together without buying new parts except gasket kits and Bearings.

Pistons stuck at bottom were delt with by putting a Hydraulic Jack under one of the Rod Bearings lower camps (this ruined the Rod Bearing) and attempting to turn the crank to move the stuck pistion. (These were generator set engines mounted on a steel frame.)
Unfortunately with Mercedes and the Engine in the Car you cannot get to the crank case except for the limited area under the littl oil pan.

turbobenz · #14 05-29-2009, 03:31 PM

I would try penetrating oil and a crowbar on the starter teeth like someone else suggested.

If that fails, 24volts to the starter

whunter · #15 05-29-2009, 03:38 PM

Quote:

Originally Posted by strelnik

I am buying a diesel (OM615) that has sat under cover for several years but ran well when it was in a car. It was removed because the body rotten tho' the drive train was good. It is now sticking.

I'd be interested in all the suggestions for what to do before attempting to unstick it.

The obvious things are:
1. Change all oil and oil filter
2. Change all fuel filters and reprime
3. Check and or change the glow plugs
4. Drain and refill the oil sump in the injection pump.

I have been advised that the only thing to do is use lot of WD40 in the cylinders after removing the injectors, and I have some doubts about that.

Others have said I MUST pull the head.

I favor adding a thin oil to every cylinder for about a week through the injector ports with a long injector-type oil can and slowly turning by hand.

Others have suggested using Rislone instead of oil, still others Ford ATF (Type F) because of its higher detergent content, compared to Dexron.

Whaddaya think?

I'm sure this thread will provide some good advice and some good discussion.

Thanks,
S (still looking for a running OM 636 for the 170DS to be)

You know the number..